cant use pin 09 of port 0. &uicr { nfct-pins-as-gpios; }; doesn't work.

[shlomots]

Hello,
my custom board is using pin 09 to communicate through uart.
I want to check that uart is working on this custom board.
First, I tried to create a simple uart application that sends chars to another board, at this stage I am checking it with terra term.
the code logic works, but when I try to use pin 09 of port 1 as tx, it doesn't,
now I know that this pin is by default used by nfct, and if I want to use it I need to add 

&uicr {

    nfct-pins-as-gpios;

};

 
to the overlay file.
for some reason, this doesn't suffice.
Is there anything else I should do in order to use this pin?

thanks in advance, 
-shlomo

[Einar Thorsrud]

Hi,

What you have added with nfct-pins-as-gpios is all that is needed. You can double check that the pins are configured as GPIO pins by reading out the NFCPINS with a debugger. If the LSb is 0, the pin is confgiured as a GPIO an dthe issue is someting else. Could you try to configure the pin as an output and simply toggle it to see if that works?

PS: On the DK, you need to solder a solder bridge to access the GPIO on a pin header as by default the NFC pins are only routed to the NFC antenna connector, but sa you are using a custom board that is not relevant in this case.

[shlomots]

Actually, I see that I wasn't 100 percent clear.

The app i have written and trying to communicate with is running on a dk. I wanted first to establish communication between two dk's.

It didnt work on the dk's so i didnt try on custom board yet.

Could you expand about what the solder bridge on the dk?

[Einar Thorsrud]

Hi,

I see, if you are on a DK, this is expected. You need to solder or populate a 0 ohm resistor on R43, see the Configuring NFC pins as GPIOs in the DK documentation.

[shlomots]

Awesome, I will try that. 

Thank you!